Purple
Martinsare the
largest swallow in North America. The western subspecies
(Progne subis
arboricola) is threatened in British
Columbia. Historically, Western Purple Martins nested in
woodpecker holes in old trees or snags in open woodland areas or near freshwater
and likely made extensive use of fire-killed stands. Due to logging, fire
prevention, snag removal, burned timber salvage and agricultural and urban
development throughout their original breeding range around the Georgia Basin, this habitat has been
lost.
Resident populations of non-native European Starlings and House Sparrows also
provide strong competition for any remaining nest cavities.

As other suitable habitat was lost, martins shifted to nesting in woodpecker
cavities in abundant old and decaying untreated wooden pilings remaining from
early industrial development around the Strait of Georgia (as well as in Puget
Sound, WA, and along the lower Columbia River), and as these old pilings fell or
were replaced with creosote-treated pilings (and later steel and concrete
pilings), in which woodpeckers cannot excavate nest cavities, their numbers
steadily declined due to lack of usable nest cavity sites. By
the early 1980s the BC population of Western Purple Martins was reduced to less than 10
breeding pairs.

Since then, the British Columbia population of Purple Martins has
rebounded to over 200 pairs by 2002 and ~650 pairs by 2007. This is due to the volunteer-based nest box program begun in the
Georgia Basin area in 1986, as well as a similar program begun a decade earlier in Puget Sound, Washington, in 1975.

The BC population increased dramatically between 2003 and 2006,
due in part to good weather conditions throughout the breeding season, resulting in an ample food supply of flying insects for
both adults and nestlings. As for other swallows, the nesting success of Purple Martins is highly sensitive to adverse weather-induced
reduction in food supply availability. An article about the history of the recovery of Purple Martins in BC, up to and including 2004,
was printed in BirdWatch Canada (winter 2005 No. 30, p.21-22), a publication of Bird Studies Canada and is available
here in .PDF format.

After stalling for several years at 500-650 pairs (2006-10)
due to low fledgling production and subadult (yearling) recruitment as a result of 4-5 nesting seasons with long cool wet
periods that limited food availability and reduced nestling survival, the BC population again began to increase, reaching
950 pairs in 2013 and likely to exceed 1,000 pairs in 2014.

Since 2002, GBEARS has provided overall co-coordination and
scientific direction, monitoring and management of the BC Purple Martin Stewardship and Recovery Program. As part of this
program, nest boxes are being put up at potential new colony sites as well as existing ones. Each box is numbered with a unique
number that includes the year of installation. Abundance, nesting success and production at each colony site are monitored and
recorded.

Also, Western Purple Martin nestlings from each colony are banded
with
numbered bands which allow us to track their migratory routes, dispersal and
recruitment and colony and nest box selection throughout their lives, without
further capture or disturbance. Bands
read with spotting scopes in later years indicate that martins fledged from any
one colony return to nest at many different colonies throughout the Strait of
Georgia and Puget Sound, providing extensive genetic mixing within at least the
BC and Puget Sound, WA, population, with occasional dispersal to Oregon and
possibly California.

In 2007 a 10-year old adult male banded in 1997
and a 9-year old adult female banded in 1998 were both identified from their band numbers and nested successfully. The female returned and nested
successfully again in 2008 as a 10-year old bird. This female and a second
previously unseen female returned and nested as 11-year old birds in 2009, but
neither nest was successful and neither of these birds has been seen again
since. These are believed to be western longevity
records to date for males and females in the wild. Most martins that survive their first
winter live only 2-3 years and very few exceed 5 years of age.

In addition, this
long term banding study is now providing valuable information on the population
dynamics and variable age composition of the BC population, which is important
for understanding changes in the rate of growth or decline of the population due
to variations in nesting success, fledgling production and recruitment of new
subadult birds, and thus the progress and overall success of the recovery
program. Some of these results may be applicable generally to other equally
weather-dependent but less closely monitored swallow populations as well. This
long-term population dynamics and age composition study is unique for Purple
Martins in Canada and for Western Purple Martins in western North America, and
has been supported in part by the Canadian Wildlife Service, The Baillie Fund of
Bird Studies Canada, The Canadian Wildlife Foundation and Timber West..

In 2005 and 2006 a survey of remaining historic and potential
new freshwater nesting sites was conducted in preparation for re-introducing
Western Purple Martins into naturally occurring nesting cavity situations in the wild.
In general, suitable freshwater sites with snags for mounting a few "starter"
nest boxes and containing natural cavities for new colonies to expand into
as they grow were very scarce, particularly on south Vancouver Is. and in the
Lower Mainland. Many former nesting sites in the wild have been lost to various
forms of development, the snags have fallen or been removed and very little
suitable 'traditional' nesting habitat remains in the Georgia Basin. So far 15
freshwater nest box sites have been established in the Lower Mainland and
lower Fraser Valley and 10 have been initiated on the east coast of Vancouver Island and the Gulf Islands,
some on pilings and others on flooded snags (at right, Crofton Lake). Three of
these sites were first occupied by Western Purple Martins in 2013, at Westwood
Lake in Nanaimo and Comox Lake near Courtenay on east Vancouver Island, and at
Burnaby lake in Vancouver on the BC Lower Mainland. We hope to see this trend
continue in the next few years.

There are currently active colonies established at the locations
shown in the following map (2015):

* Shaded area indicates historic breeding range of Purple Martin in BC;
colonies in Puget Sound, WA, (dark grey) not shown. New nesting sites in the
lower Fraser River valley east of
Vancouver at Mission (2007-8, 2013-15) and Harrison Mills (2013-15) and in Johnstone Strait
between Port
Neville and Port McNeill (2013-15) also not shown.Nest Box Construction
and Mounting Plans

If you would like to build your own Western Purple Martin
nest boxes, click here for the nest box plans and
here
for instructions on how to mount them. If you want copies of these document files, save them to a file on your computer and print them from that file.
(Tip: If the drawings appear difficult to read, click on them to increase screen
zoom magnification.) Please
contact us
before putting up nest boxes, so we can keep track of where they are and also
provide any help or further information you might need.

When choosing suitable nest box locations for attracting Western Purple Martins, it's
important to keep in mind that they like to nest in
clusters of single boxes placed in open spaces beside or over water
(rather than the familiar multi-compartment "condos" placed over land for the
eastern subspecies). In BC eastern martin apartment houses are NOT accepted by
western martins and tend to be taken over by non-native European Starlings and House
Sparrows, which then exclude martins and become part of the problem. They show a strong preference
for open coastal locations and do not accept nest boxes placed in typical upland
"back yard" situations, but are beginning to show interest in sites
over or bordering fresh water.

As
of 2013, almost all occupied Western Purple Martin colonies in BC are located on pilings
along the marine coastal foreshore in bays, estuaries, and marinas,
within or beyond the intertidal zone within the Georgia Basin. They are also at least 50-100m away
from trees and other tall structures on the foreshore that might provide hunting
perches and approach cover for ambush predators, mainly small hawks.

Apart from 1-2 early site colonizations along the lower Fraser River, east of Vancouver
(after a 40+ year absence!) in 2006-07, and more recent colonization (2013) at
several lakes near the coast (Westwood Lake in Nanaimo, Comox Lake near
Courtenay and Burnaby Lake in Vancouver), there are no nest box sites in use inland of the marine coast in the Georgia Basin. Purple Martins
in BC historically used
fresh water sites for nesting here and results of monitoring during the 2013
nesting season indicate we are beginning to have some success re-introducing them to similar
suitable nest sites without House Sparrow populations or large numbers of
Starlings. For this reason we encourage placement of nest box clusters on snags,
pilings, and other offshore structures at fresh water sites on lakes and
marshes. It may take a few more years for them to adapt to this situation, but if
they do take a liking to your fresh water colony site please let us know.

It's also important to note that, unlike other native cavity-nesting members of
the swallow family that nest in both the wild and in human-supplied nest boxes,
Western Purple Martins in BC are currently completely dependant on human-provided nest
boxes and would not be nesting in the province at all without them. (The nearest known snag-nesting site is at Fort Lewis in southern Puget Sound, Washington.) One long term objective and major challenge of the Stewardship and Recovery Program in BC
is to re-introduce martins to nest sites in their original habitat (or a
reasonable modern equivalent) where they may become self-sustaining, rather than develop a population of
semi-domesticated birds entirely dependant on ongoing human provision and
maintenance of nest sites. Recovery results so far suggest this goal is very
likely achievable in time, given a continued strong stewardship effort,
continued population growth and the existence of sufficient natural cavities in
snags in suitable habitat in the wild. Recent documentation of Western Purple
Martins nesting successfully in woodpecker cavities in mechanical
harvester-topped and killed "created snags" in central Oregon (M. Hane, unpub.
data) provides additional promise in this regard.

The WPMWG has served since 1998 as an international coordinating body for researchers, government agency management personnel, non-profit groups, bird banders and volunteers working toward the study, conservation and recovery of the western subspecies populations of Purple Martin breeding west of the Rocky Mountains in Canada and the USA. Members of the group meet annually (usually at Vancouver, Washington) to share research and monitoring results, plan further studies and coordinate leg banding, conservation and recovery efforts. Secretary: Stan Kostka

These are preliminary general protocols developed by the WPMWG to provide consistent and reliable methods of assessment of western Purple Martin nest site use, nesting success and productivity at inaccessible cavities. They are provided as working documents for application, evaluation and modification to specific cavity nesting situations as needed. If you apply either of these protocols and find them useful, discover a need for modifications or additions, or require further information, please
contact us and let us know, so we can track usage and provide updates and other Purple Martin monitoring and recovery workers may benefit from your experience.”